1. Field of the Invention
The field of the invention relates generally to osteogenic cells and the formation of bone and boney tissue in mammalian species. Specifically, the invention concerns a novel family of proteins, and nucleic acids encoding those proteins, that enhances the efficacy of bone mineralization in vitro and in vivo. The invention provides methods for treating a variety of pathological conditions associated bone and boney tissue, such as, for example, spine fusion, fracture repair and osteoporosis.
2. Description of the Related Art
Osteoblasts are thought to differentiate from pluripotent mesenchymal stem cells. The maturation of an osteoblast results in the secretion of an extracellular matrix which can mineralize and form bone. The regulation of this complex process is not well understood but is thought to involve a group of signaling glycoproteins known as bone morphogenetic proteins (BMPs). These proteins have been shown to be involved with embryonic dorsal-ventral patterning, limb bud development, and fracture repair in adult animals. B. L. Hogan, Genes and Develop., 10:1580 (1996). This group of transforming growth factor-beta superfamily secreted proteins has a spectrum of activities in a variety of cell types at different stages of differentiation; differences in physiological activity between these closely related molecules have not been clarified. D. M. Kingsley, Trends Genet., 10:16 (1994).
To better discern the unique physiological role of different BMP signaling proteins, we recently compared the potency of BMP-6 with that of BMP-2 and BMP-4, for inducing rat calvarial osteoblast differentiation. Boden et al., Endocrinology, 137:3401 (1996). We studied this process in first passage (secondary) cultures of fetal rat calvaria that require BMP or glucocorticoid for initiation of differentiation. In this model of membranous bone formation, glucocorticoid (GC) or a BMP will initiate differentiation to mineralized bone nodules capable of secreting osteocalcin, the osteoblast-specific protein. This secondary culture system is distinct from primary rat osteoblast cultures which undergo spontaneous differentiation. In this secondary system, glucocorticoid resulted in a ten-fold induction of BMP-6 mRNA and protein expression which was responsible for the enhancement of osteoblast differentiation. Boden et al., Endocrinology, 138:2920 (1997).
In addition to extracellular signals, such as the BMPs, intracellular signals or regulatory molecules may also play a role in the cascade of events leading to formation of new bone. One broad class of intracellular regulatory molecules are the LIM proteins, which are so named because they possess a characteristic structural motif known as the LIM domain. The LIM domain is a cysteine-rich structural motif composed of two special zinc fingers that are joined by a 2-amino acid spacer. Some proteins have only LIM domains, while others contain a variety of additional functional domains. LIM proteins form a diverse group, which includes transcription factors and cytoskeletal proteins. The primary role of LIM domains appears to be in mediating protein-protein interactions, through the formation of dimers with identical or different LIM domains, or by binding distinct proteins.
In LIM homeodomain proteins, that is, proteins having both LIM domains and a homeodomain sequence, the LIM domains function as negative regulatory elements. LIM homeodomain proteins are involved in the control of cell lineage determination and the regulation of differentiation, although LIM-only proteins may have similar roles. LIM-only proteins are also implicated in the control of cell proliferation since several genes encoding such proteins are associated with oncogenic chromosome translocations.
Humans and other mammalian species are prone to diseases or injuries that require the processes of bone repair and/or regeneration. For example, treatment of fractures would be improved by new treatment regimens that could stimulate the natural bone repair mechanisms, thereby reducing the time required for the fractured bone to heal. In another example, individuals afflicted with systemic bone disorders, such as osteoporosis, would benefit from treatment regimens that would results in systemic formation of new bone. Such treatment regimens would reduce the incidence of fractures arising from the loss of bone mass that is a characteristic of this disease.
For at least these reasons, extracellular factors, such as the BMPs, have been investigated for the purpose of using them to stimulate formation of new bone in vivo. Despite the early successes achieved with BMPs and other extracellular signalling molecules, their use entails a number of disadvantages. For example, relatively large doses of purified BMPs are required to enhance the production of new bone, thereby increasing the expense of such treatment methods. Furthermore, extracellular proteins are susceptible to degradation following their introduction into a host animal. In addition, because they are typically immunogenic, the possibility of stimulating an immune response to the administered proteins is ever present.
Due to such concerns, it would be desirable to have available treatment regimens that use an intracellular signalling molecule to induce new bone formation. Advances in the field of gene therapy now make it possible to introduce into osteogenic precursor cells, that is, cells involved in bone formation, nucleotide fragments encoding intracellular signals that form part of the bone formation process. Gene therapy for bone formation offers a number of potential advantages: (1) lower production costs; (2) greater efficacy, compared to extracellular treatment regiments, due to the ability to achieve prolonged expression of the intracellular signal; (3) it would by-pass the possibility that treatment with extracellular signals might be hampered due to the presence of limiting numbers of receptors for those signals; (4) it permits the delivery of transfected potential osteoprogenitor cells directly to the site where localized bone formation is required; and (5) it would permit systemic bone formation, thereby providing a treatment regimen for osteoporosis and other metabolic bone diseases.
The present invention seeks to overcome the drawbacks in the prior art by providing novels compositions and methods for inducing bone formation using an intracellular signalling molecule that participates early in the cascade of events that leads to bone formation. Applicants have discovered 10-4/RLMP (SEQ ID NO:1, SEQ ID NO:2), a novel LIM gene with a sequence originally isolated from stimulated rat calvarial osteoblast cultures. The gene has been cloned, sequenced and assayed for its ability to enhance the efficacy of bone mineralization in vitro. The protein RLMP affects mineralization of bone matrix as well as differentiation of cells into the osteoblast lineage. Unlike other known cytokines, for example, BMPs, RLMP is not a secreted protein, but is instead an intracellular signaling molecule. This feature has the advantage of providing intracellular signaling amplification as well as easier assessment of transfected cells. It is also suitable for more efficient and specific in vivo applications. Suitable clinical applications include enhancement of bone repair in fractures, bone defects, bone grafting, and normal homeostasis in patients presenting with osteoporosis.
Applicants have also cloned, sequenced and deduced the amino acid sequence of a corresponding human protein, named human LMP-1. The human protein demonstrates enhanced efficacy of bone mineralization in vitro and in vivo.
In addition, the applicants have characterized a truncated (short) version of LMP-1, termed HLMP-1 s. This short version resulted from a point mutation in one source of a cDNA clone, providing a stop codon which truncated the protein. The short version (LMP-1 s) is fully functional when expressed in cell culture and in vivo.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the methods and compositions of matter particularly pointed out in the written description and claims hereof.
In one broad aspect, the invention relates to an isolated nucleic acid molecule comprising a nucleic acid sequence encoding any LIM mineralization protein, wherein the nucleic acid molecule hybridizes under standard conditions to a nucleic acid molecule complementary to the full length of SEQ. ID NO:25, and wherein the molecule hybridizes under highly stringent conditions to a nucleic acid molecule complementary to the full length of SEQ. ID NO:26. In a specific aspect, the isolated nucleic acid molecule encodes HLMP-1, HLMP-1 s or RLMP. In addition, the invention is directed to vectors comprising these nucleic acid molecules, as well as host cells comprising the vectors. In another specific aspect, the invention relates to the proteins themselves.
In a second broad aspect, the invention relates to antibody that is specific for LIM mineralization protein, including HLMP-1, HLMP-1 s and RLMP. In one specific ascpect, the antibody is a polyclonal antibody. In another specific aspect, the antibody is a monoclonal antibody.
In a third broad aspect, the invention relates to method of inducing bone formation wherein osteogenic precursor cells are transfected with an isolated nucleic acid molecule comprising a nucleotide sequence encoding LIM mineralization protein. In one specific aspect, the isolated nucleic acid molecule is in a vector, which may be a plasmid or a virus, such as adenovirus or retrovirus. The transfection may occur ex vivo or in vivo by direct injection of the isolated nucleic acid molecule. The transfected isolated nucleic acid molecule may encode HLMP-1, HLMP-1 s or RLMP.
In a further aspect, the invention relates to methods of fusing a spine by transfecting osteogenic precursor cells with an isolated nucleic acid molecule having a nucleotide sequence encoding LIM mineralization protein, admixing the transfected osteogenic precursor cells with a matrix and contacting the matrix with the spine.
In yet another aspect, the invention relates to methods for inducing systemic bone formation by stable transfection of host cells with the vectors of the invention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The present invention relates to novel mammalian LIM proteins, herein designated LIM mineralization proteins, or LMP. The invention relates more particularly to human LMP, known as HLMP or HLMP-1. The applicants have discovered that these proteins enhance bone mineralization in mammalian cells grown in vitro. When produced in mammals, LMP also induces bone formation in vivo.
Ex vivo transfection of bone marrow cells, osteogenic precursor cells or mesenchymal stem cells with nucleic acid that encodes LMP or HLMP, followed by reimplantation of the transfected cells in the donor, is suitable for treating a variety of bone-related disorders or injuries. For example, one can use this method to: augment long bone fracture repair; generate bone in segmental defects; provide a bone graft substitute for fractures; facilitate tumor reconstruction or spine fusion; and provide a local treatment (by injection) for weak or osteoporotic bone, such as in osteoporosis of the hip, vertebrae, or wrist. Transfection with LMP or HLMP-encoding nucleic acid is also useful in: the percutaneous injection of transfected marrow cells to accelerate the repair of fractured long bones; treatment of delayed union or non-unions of long bone fractures or pseudoarthrosis of spine fusions; and for inducing new bone formation in avascular necrosis of the hip or knee.
In addition to ex vivo-based methods of gene therapy, transfection of a recombinant DNA vector comprising a nucleic acid sequence that encodes LMP or HLMP can be accomplished in vivo. When a DNA fragment that encodes LMP or HLMP is inserted into an appropriate viral vector, for example, an adenovirus vector, the viral construct can be injected directly into a body site were endochondral bone formation is desired. By using a direct, percutaneous injection to introduce the LMP or HLMP sequence stimulation of bone formation can be accomplished without the need for surgical intervention either to obtain bone marrow cells (to transfect ex vivo) or to reimplant them into the patient at the site where new bone is required. Alden et al., Neurosurgical Focus (1998), have demonstrated the utility of a direct injection method of gene therapy using a cDNA that encodes BMP-2, which was cloned into an adenovirus vector.
It is also possible to carry out in vivo gene therapy by directly injecting into an appropriate body site, a naked, that is, unencapsulated, recombinant plasmid comprising a nucleic acid sequence that encodes HLMP. In this embodiment of the invention, transfection occurs when the naked plasmid DNA is taken up, or internalized, by the appropriate target cells, which have been described. As in the case of in vivo gene therapy using a viral construct, direct injection of naked plasmid DNA offers the advantage that little or no surgical intervention is required. Direct gene therapy, using naked plasmid DNA that encodes the endothelial cell mitogen VEGF (vascular endothelial growth factor), has been successfully demonstrated in human patients. Baumgartner et al., Circulation, 97(12):1114-23 (1998).
By using an adenovirus vector to deliver LMP into osteogenic cells, transient expression of LMP is achieved. This occurs because adenovirus does not incorporate into the genome of target cells that are transfected. Transient expression of LMP, that is, expression that occurs during the lifetime of the transfected target cells, is sufficient to achieve the objects of the invention. Stable expression of LMP, however, can occur when a vector that incorporates into the genome of the target cell is used as a delivery vehicle. Retrovirus-based vectors, for example, are suitable for this purpose.
Stable expression of LMP is particularly useful for treating various systemic bone-related disorders, such as osteoporosis and osteogenesis imperfecta. For this embodiment of the invention, in addition to using a vector that integrates into the genome of the target cell to deliver an LMP-encoding nucleotide sequence into target cells, LMP expression is placed under the control of a regulatable promoter. For example, a promoter that is turned on by exposure to an exogenous inducing agent, such as tetracycline, is suitable. Using this approach, one can stimulate formation of new bone on a systemic basis by administering an effective amount of the exogenous inducing agent. Once a sufficient quantity of bone mass is achieved, administration of the exogenous inducing agent is discontinued. This process may be repeated as needed to replace bone mass lost, for example, as a consequence of osteoporosis.
Antibodies specific for HLMP are particularly suitable for use in methods for assaying the osteoinductive, that is, bone-forming, potential of patient cells. In this way one can identify patients at risk for slow or poor healing of bone repair. Also, HLMP-specific antibodies are suitable for use in marker assays to identify risk factors in bone degenerative diseases, such as, for example, osteoporosis.
Following well known and conventional methods, the genes of the present invention are prepared by ligation of nucleic acid segments that encode LMP to other nucleic acid sequences, such as cloning and/or expression vectors. Methods needed to construct and analyze these recombinant vectors, for example, restriction endonuclease digests, cloning protocols, mutagenesis, organic synthesis of oligonucleotides and DNA sequencing, have been described. For DNA sequencing DNA, the dieoxyterminator method is the preferred.
Many treatises on recombinant DNA methods have been published, including Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, 2nd edition (1988), Davis et al., Basic Methods in Molecular Biology, Elsevier (1986), and Ausubel et al., Current Protocols in Molecular Biology, Wiley Interscience (1988). These reference manuals are specifically incorporated by reference herein.
Primer-directed amplification of DNA or cDNA is a common step in the expression of the genes of this invention. It is typically performed by the polymerase chain reaction (PCR). PCR is described in U.S. Pat. No. 4,800,159 to Mullis et al. and other published sources. The basic principle of PCR is the exponential replication of a DNA sequence by successive cycles of primer extension. The extension products of one primer, when hybridized to another primer, becomes a template for the synthesis of another nucleic acid molecule. The primer-template complexes act as substrate for DNA polymerase, which in performing its replication function, extends the primers. The conventional enzyme for PCR applications is the thermostable DNA polymerase isolated from Thermus aquaticus, or Taq DNA polymerase.
Numerous variations of the basic PCR method exist, and a particular procedure of choice in any given step needed to construct the recombinant vectors of this invention is readily performed by a skilled artisan. For example, to measure cellular expression of 10-4/RLMP, RNA is extracted and reverse transcribed under standard and well known procedures. The resulting cDNA is then analyzed for the appropriate mRNA sequence by PCR.
The gene encoding the LIM mineralization protein is expressed in an expression vector in a recombinant expression system. Of course, the constructed sequence need not be the same as the original, or its complimentary sequence, but instead may be any sequence determined by the degeneracy of the DNA code that nonetheless expresses an LMP having bone forming activity. Conservative amino acid substitutions, or other modifications, such as the occurrance of an amino-terminal methionine residue, may also be employed.
A ribosome binding site active in the host expression system of choice is ligated to the 5xe2x80x2 end of the chimeric LMP coding sequence, forming a synthetic gene. The synthetic gene can be inserted into any one of a large variety of vectors for expression by ligating to an appropriately linearized plasmid. A regulatable promoter, for example, the E. coli lac promoter, is also suitable for the expression of the chimeric coding sequences. Other suitable regulatable promoters include trp, tac, recA, T7 and lambda promoters.
DNA encoding LMP is transfected into recipient cells by one of several standard published procedures, for example, calcium phosphate precipitation, DEAE-Dextran, electroporation or protoplast fusion, to form stable transformants. Calcium phosphate precipitation is preferred, particularly when performed as follows.
DNAs are coprecipitated with calcium phosphate according to the method of Graham and Van Der, Virology, 52:456 (1973), before transfer into cells. An aliquot of 40-50 xcexcg of DNA, with salmon sperm or calf thymus DNA as a carrier, is used for 0.5xc3x97106 cells plated on a 100 mm dish. The DNA is mixed with 0.5 ml of 2xc3x97Hepes solution (280 mM NaCl, 50 mM Hepes and 1.5 mM Na2HPO4, pH 7.0), to which an equal volume of 2xc3x97CaCl2 (250 mM CaCl2 and 10 mM Hepes, pH 7.0) is added. A white granular precipitate, appearing after 30-40 minutes, is evenly distributed dropwise on the cells, which are allowed to incubate for 4-16 hours at 37xc2x0 C. The medium is removed and the cells shocked with 15% glycerol in PBS for 3 minutes. After removing the glycerol, the cells are fed with Dulbecco""s Minimal Essential Medium (DMEM) containing 10% fetal bovine serum. DNA can also be transfected using: the DEAE-Dextran methods of Kimura et al., Virology, 49:394 (1972) and Sompayrac et al., Proc. Natl. Acad. Sci. USA, 78:7575 (1981); the electroporation method of Potter, Proc. Natl. Acad. Sci. USA, 81:7161 (14984); and the protoplast fusion method of Sandri-Goddin et al., Molec. Cell. Biol., 1:743 (1981).
Phosphoramidite chemistry in solid phase is the preferred method for the organic synthesis of oligodeoxynucleotides and polydeoxynucleotides. In addition, many other organic synthesis methods are available. Those methods are readily adapted by those skilled in the art to the particular sequences of the invention.
The present invention also includes nucleic acid molecules that hybridize under standard conditions to any of the nucleic acid sequences encoding the LIM mineralization proteins of the invention. xe2x80x9cStandard hybridization conditionsxe2x80x9d will vary with the size of the probe, the background and the concentration of the nucleic acid reagents, as well as the type of hybridization, for example, in situ, Southern blot, or hybrization of DNA-RNA hybrids (Northern blot). The determination of xe2x80x9cstandard hybridization conditionsxe2x80x9d is within the level of skill in the art. For example, see U.S. Pat. No. 5,580,775 to Fremeau et al., herein incorporated by reference for this purpose. See also, Southern, E. M., J. Mol. Biol., 98:503 (1975), Alwine et al., Meth. Enzymol., 68:220 (1979), and Sambrook et al., Molecular Cloning: A laboratory Manual, 2nd edition, pp. 7.19-7.50, Cold Spring Harbor Press (1989).
One preferred set of standard hybrization conditions involves a blot that is prehybridized at 42xc2x0 C. for 2 hours in 50% formamide, 5xc3x97SSPE (150 nM NaCl, 10 mM Na H2 PO4[pH 7.4], 1 mM EDTA [pH 8.0]), 5xc3x97Denhardt""s solution (20 mg Ficoll, 20 mg polyvinylpyrrolidone and 20 mg BSA per 100 ml water), 10% dextran sulphate, 1% SDS and 100 xcexcg/ml salmon sperm DNA. A 32P-labelled cDNA probe is added, and hybridization is continued for 14 hours. Afterward, the blot is washed twice with 2xc3x97SSPE, 0.1% SDS for 20 minutes at 22xc2x0 C., followed by a 1 hour wash at 65xc2x0 C. in 0.1xc3x97SSPE, 0.1% SDS. The blot is then dried and exposed to x-ray film for 5 days in the presence of an intensifying screen.
Under xe2x80x9chighly stringent conditions,xe2x80x9d a probe will hybridize to its target sequence if those two sequences are substantially identical. As in the case of standard hybridization conditions, one of skill in the art can, given the level of skill in the art and the nature of the particular experiment, determine the conditions under which only substantially identical sequences will hybridize.
Another aspect of the invention includes the proteins encoded by the nucleic acid sequences. In still another embodiment, the invention relates to the identification of such proteins based on anti-LMP antibodies. In this embodiment, protein samples are prepared for Western blot analysis by lysing cells and separating the proteins by SDS-PAGE. The proteins are transferred to nitrocellulose by electroblotting as described by Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons (1987). After blocking the filter with instant nonfat dry milk (1 gm in 100 ml PBS), anti-LMP antibody is added to the filter and incubated for 1 hour at room temperature. The filter is washed thoroughly with phosphate buffered saline (PBS) and incubated with horseradish peroxidase (HRPO)-antibody conjugate for 1 hour at room temperature. The filter is again washed thoroughly with PBS and the antigen bands are identified by adding diaminobenzidine (DAB).
Monospecific antibodies are the reagent of choice in the present invention, and are specifically used to analyze patient cells for specific characteristics associated with the expression of LMP. xe2x80x9cMonospecific antibodyxe2x80x9d as used herein is defined as a single antibody species or multiple antibody species with homogenous binding characteristics for LMP. xe2x80x9cHomogeneous bindingxe2x80x9d as used herein refers to the ability of the antibody species to bind to a specific antigen or epitope, such as those associated with LMP, as described above. Monospecific antibodies to LMP are purified from mammalian antisera containing antibodies reactive against LMP or are prepared as monoclonal antibodies reactive with LMP using the technique of Kohler and Mistein, Nature, 256:495-97 (1975). The LMP specific antibodies are raised by immunizing animals such as, for example, mice, rats, guinea pigs, rabbits, goats or horses, with an appropriate concentration of LMP either with or without an immune adjuvant.
In this process, preimmune serum is collected prior to the first immunization. Each animal receives between about 0.1 mg and about 1000 mg of LMP associated with an acceptable immune adjuvant, if desired. Such acceptable adjuvants include, but are not limited to, Freund""s complete, Freund""s incomplete, alum-precipitate, water in oil emulsion containing Corynebacterium parvum and tRNA adjuvants. The initial immunization consists of LMP in, preferably, Freund""s complete adjuvant injected at multiple sites either subcutaneously (SC), intraperitoneally (IP) or both. Each animal is bled at regular intervals, preferably weekly, to determine antibody titer. The animals may or may not receive booster injections following the initial immunization. Those animals receiving booster injections are generally given an equal amount of the antigen in Freund""s incomplete adjuvant by the same route. Booster injections are given at about three week intervals until maximal titers are obtained. At about 7 days after each booster immunization or about weekly after a single immunization, the animals are bled, the serum collected, and aliquots are stored at about xe2x88x9220xc2x0 C.
Monoclonal antibodies (mAb) reactive with LMP are prepared by immunizing inbred mice, preferably Balb/c mice, with LMP. The mice are immunized by the IP or SC route with about 0.1 mg to about 10 mg, preferably about I mg, of LMP in about 0.5 ml buffer or saline incorporated in an equal volume of an acceptable adjuvant, as discussed above. Freund""s complete adjuvant is preferred. The mice receive an initial immunization on day 0 and are rested for about 3-30 weeks. Immunized mice are given one or more booster immunizations of about 0.1 to about 10 mg of LMP in a buffer solution such as phosphate buffered saline by the intravenous (IV) route. Lymphocytes from antibody-positive mice, preferably splenic lymphocytes, are obtained by removing the spleens from immunized mice by standard procedures known in the art. Hybridoma cells are produced by mixing the splenic lymphocytes with an appropriate fusion partner, preferably myeloma cells, under conditions which will allow the formation of stable hybridomas. Fusion partners may include, but are not limited to: mouse myelomas P3/NS1/Ag 4-1; MPC-11; S-194 and Sp 2/0, with Sp 2/0 being preferred. The antibody producing cells and myeloma cells are fused in polyethylene glycol, about 1000 mol. wt., at concentrations from about 30% to about 50%. Fused hybridoma cells are selected by growth in hypoxanthine, thymidine and aminopterin in supplemented Dulbecco""s Modified Eagles Medium (DMEM) by procedures known in the art. Supernatant fluids are collected from growth positive wells on about days 14, 18, and 21, and are screened for antibody production by an immunoassay such as solid phase immunoradioassay (SPIRA) using LMP as the antigen. The culture fluids are also tested in the Ouchterlony precipitation assay to determine the isotype of the mAb. Hybridoma cells from antibody positive wells are cloned by a technique such as the soft agar technique of MacPherson, xe2x80x9cSoft Agar Techniquesxe2x80x9d, in Tissue Culture Methods and Applications, Kruse and Paterson (eds.), Academic Press (1973). See, also, Harlow et al., Antibodies: A Laboratory Manual, Cold Spring Laboratory (1988).
Monoclonal antibodies may also be produced in vivo by injection of pristane-primed Balb/c mice, approximately 0.5 ml per mouse, with about 2xc3x97106 to about 6xc3x97106 hybridoma cells about 4 days after priming. Ascites fluid is collected at approximately 8-12 days after cell transfer and the monoclonal antibodies are purified by techniques known in the art.
In vitro production in anti-LMP mAb is carried out by growing the hydridoma cell line in DMEM containing about 2% fetal calf serum to obtain sufficient quantities of the specific mAb. The mAb are purified by techniques known in the art.
Antibody titers of ascites or hybridoma culture fluids are determined by various serological or immunological assays, which include, but are not limited to, precipitation, passive agglutination, enzyme-linked immunosorbent antibody (ELISA) technique and radioimmunoassay (RIA) techniques. Similar assays are used to detect the presence of the LMP in body fluids or tissue and cell extracts.
It is readily apparent to those skilled in the art that the above described methods for producing monospecific antibodies may be utilized to produce antibodies specific for polypeptide fragments of LMP, full-length nascent LMP polypeptide, or variants or alleles thereof.
On Jul. 22, 1997, a sample of 10-4/RLMP in a vector designated pCMV2/RLMP (which is vector pRc/CMV2 with insert 10-4 clone/RLMP) was deposited with the American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, Md. 20852. The culture accession number for that deposit is 209153. On Mar. 19, 1998, a sample of the vector pHis-A with insert HLPM-1 s was deposited at the American Type Culture Collection. The culture accession number for that deposit is 209698. These deposits, made under the requirements of the Budapest Treaty, will be maintained in the ATCC for at least 30 years and will be made available to the public upon the grant of a patent disclosing them. It should be understood that the availability of a deposit does not constitute a license to practice the subject invention in derogation of patent rights granted by government action.
In assessing the nucleic acids, proteins, or antibodies of the invention, enzyme assays, protein purification, and other conventional biochemical methods are employed. DNA and RNA are analyzed by Southern blotting and Northern blotting techniques, respectively. Typically, the samples analyzed are size fractionated by gel electrophoresis. The DNA or RNA in the gels are then transferred to nitrocellulose or nylon membranes. The blots, which are replicas of sample patterns in the gels, were then hybridized with probes. Typically, the probes are radiolabelled, preferably with 32P, although one could label the probes with other signal-generating molecules known to those in the art. Specific bands of interest can then be visualized by detection systems, such as autoradiography.